3D Printed Gear Serves Seven Months Hard Labor

October 20, 2017 by Tom Nardi 32 Comments

Even the staunchest 3D printing supporter would have to concede that in general, the greatest strength of 3D printing is not in the production of final parts, but in prototyping. Sure you can make functional prints, as the pages of this site will attest; but few would argue that you wouldn’t be better off getting your design cut out of metal or injection molded if you planned on putting the part into service over the long term. Especially if the part was to be subjected to rough service in an industrial setting.

While that’s valid advice, it certainly isn’t the definitive word on the issue. Just because a part is printed in plastic on a desktop 3D printer doesn’t necessarily mean it can’t be put into real service, at least for as long as it takes to get proper replacement parts. A recent success story from [bloomautomatic] serves as a perfect example, when one of the gears in his MIG welder split, he decided to try and print up a replacement in PLA while he waited for the nylon gear to get shipped out to him. Fast forward seven months and approximately 80,000 welds later, and [bloomautomatic] reports it’s finally time to install those replacement gears he ordered.

In the pictures [bloomautomatic] posted you can see the printed gear finally wore down to the point the teeth were essentially gone where they meshed with their metal counterparts. To those wondering why the gear was plastic to begin with, [bloomautomatic] explains that it’s intended to be a sacrificial gear that will give way instead of destroying the entire gearbox in the event of a jam. According to the original post he made when he installed the replacement gear, the part was printed in Folgertech PLA on a Monoprice Select Mini. There’s no mention of infill percentage, but with such a small part most slicers would likely have made it essentially solid to begin with.

While surviving seven tortuous months inside of the welder is no small feat, we wonder if hardier PLA formulations, treatment of the part post-printing, or even casting it in a different material couldn’t have turned this temporary part into a permanent replacement.

DIY Nintendo Switch May Be Better Than Real Thing

October 20, 2017 by Tom Nardi 20 Comments

Nintendo’s latest Zelda-playing device, the Switch, is having no problems essentially printing money for the Japanese gaming juggernaut. Its novel design that bridges the gap between portable and home console by essentially being both at the same time has clearly struck a chord with the modern gamer, and even 8 months after its release, stores are still reporting issues getting enough of the machines to meet demand.

But for our money, we’d rather have the Raspberry Pi powered version that [Tim Lindquist] slaved over for his summer project. Every part of the finished device (which he refers to as the “NinTIMdo RP”) looks professional, from the incredible job he did designing and printing the case down to the small details like the 5 LED display on the top edge that displays volume and battery level. For those of you wondering, his version even allows you to connect it to a TV; mimicking the handheld to console conversion of the real thing.

[Tim] has posted a fascinating time-lapse video of building the NinTIMdo RP on YouTube that covers every step of the process. It starts with a look at the 3D model he created in Autodesk Inventor, and then goes right into the post-printing prep work where he cleans up the printed holes with a Dremel and installs brass threaded inserts for strength. The bulk of the video shows the insane amount of hardware he managed to pack inside the case, a true testament to how much thought was put into the design.

For the software side, the Raspberry Pi is running the ever popular RetroPie along with the very slick EmulationStation front-end. There’s also a Teensy microcontroller on board that handles the low-level functions such as controlling volume, updating the LED display, and mapping the physical buttons to a USB HID device the Raspberry Pi can understand.

The Teensy source code as well as the 3D models of the case have been put up on GitHub, but for a project like this that’s just the tip of the iceberg. [Tim] does mention that he’s currently working on creating a full build tutorial though; so if Santa doesn’t leave a Switch under the tree for you this year, maybe he can at least give you a roll of filament and enough electronics to build your own.

While this isn’t the first time a Raspberry Pi has dressed up as a Nintendo console, it may represent the first time somebody has tried to replicate a current-generation gaming device with one.

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Enlarged Miniature Forklift

October 19, 2017 by Brian McEvoy 19 Comments

How do you classify something that is gigantic and miniature at the same time? LEGO kit 850, from 1977 when it was known as an Expert Builder set, was 210 modular blocks meant to be transformed into a forklift nearly 140mm tall. [Matt Denton] scaled up the miniature pieces but it still produced a smaller-than-life forklift. This is somewhere in the creamy middle because his eight-year-old nephew can sit on it but most adults would demolish their self-esteem if they attempted the same feat.

[Matt] has been seen before building these modular sets from enlarged LEGO blocks, like his Quintuple-Sized Go-Kart. He seems to have chosen the same scale for the pieces and who wouldn’t? If you’re printing yourself a ton of LEGO blocks, it just makes sense to keep them all compatible. Isn’t combing all your sets into one mishmash the point after all? We’ll see what his nephew/co-host constructs after his uncle [Matt] leaves.

In the time-lapse video after the break, you can see how the kit goes together as easily as you would hope from home-made bricks. With that kind of repeatability and a second successful project, it’s safe to say his technique is solid and this opens the door to over-sized projects to which LEGO hasn’t published instructions.

Hackaday is bursting with LEGO projects, K’Nex projects, and even Erector set projects.

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Sacrificial Bridge Avoids 3D Printed Supports

October 17, 2017 by Donald Papp 25 Comments

[Tommy] shares a simple 3D printing design tip that will be self-evident to some, but a bit of a revelation to others: the concept of a sacrificial bridge to avoid awkward support structures. In the picture shown, the black 3D print has small bridges and each bridge has a hole. The purpose of these bits is to hold a hex nut captive in the area under the bridge; a bolt goes in through the round hole in the top.

Readers familiar with 3D printing will see right away that printing the bridges might be a problem. When a printer gets to the first layer of the bridge, it will be trying to lay filament in empty space. By itself this is not usually a problem as long as a bridge is short, flat, and featureless. Unfortunately this bridge has a hole in it, and that hole means the printer will be trying to draw circles in mid-air, rather than simply stretching filament point-to-point across a gap. One solution would be to add a small amount of support structure, but that just moves the problem. Removing small supports from enclosed spaces can be a real hassle.

To solve this [Tommy] added what he calls a “sacrificial bridge”, shown as blue in the CAD image. He essentially gives the hole a flat bottom, so that the printer first lays down a thin but solid bridge as a foundation. Then, the portion with the round hole is printed on top of that. With this small design change, the print becomes much more reliable with no support structure required.

There is a bit of post-work involved since each hole needs to be drilled out to punch through the thin sacrificial bridge underneath, but it definitely beats digging out little bits of support structure instead.

3D Prints And Food

October 17, 2017 by Al Williams 55 Comments

We recently ran a post about a cute little 3D printed elephant that could dispense booze. The design didn’t actually have the plastic touching the liquid — there was a silicone tube carrying the shots. However, it did spark a conversation at the secret Hackaday bunker about how safe it is to use 3D printed objects for food. In particular, when I say 3D printing, I’m talking fused deposition modeling. Yes, there are other technologies, but most of us are printing using filament laid out in layers with a hot nozzle.

There’s a common idea that ABS is bad in general, but that PET and PLA are no problem because there are food-safe versions of those plastics available. However, the plastic is only a small part of the total food safety picture. Let me be clear: I am not a medical professional and although my computers have run a few plastics plants in years past, I am not really an expert on polymer chemistry, either. However, I don’t use 3D printed materials to hold or handle food and while you might not drop dead if you do, you might want to reconsider.

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Stripping 3D Printed Gears For Science

October 17, 2017 by Tom Nardi 33 Comments

While 3D printing is now well on its way to becoming “boring” in the same way that a table saw or lathe is, there was a time when the media and even some early adopters would have told you that the average desktop 3D printer was perhaps only a few decades behind the kind of replicator technology we saw on the Enterprise. But as the availability of these machines increased and more people got to see one up close, reality sunk in pretty quickly.

Many have dismissed the technology as little more than a novelty, and even within the 3D printing community itself there’s a feeling that most printers are used for little more than producing “dust collectors”. Some would see this attitude as disheartening, but the hackers over at [Gear Down For What?] see it as a challenge. They’ve made it their mission to push printed parts to increasingly ridiculous heights to show just what the technology is capable of, and in their latest entry, set out to push a pair of 3D printed gearboxes to failure.

The video starts out with a head to head challenge between two of their self-designed gearboxes. As they were spun up with battery powered drills, the smaller of the two quickly gave up the ghost, stripping out at 228 lbs. The victor of the first round then went on to pull a static load, only to eventually max out the scale at an impressive 680 lbs.

The gearbox may have defeated the scale, but the goal of the experiment was to run it to failure. By rigging up a compound pulley arrangement, they were able to double the amount of force their scale could detect. With this increased capacity the gearbox was then run up to an astonishing 1,000 lbs before it started to slip.

But perhaps the most impressive: after they got the gearbox disassembled, it was discovered that only a single planet gear out of the ten had broken. Even then, judging by how the gear sheared, the issue was more likely due to poor layer adhesion during printing than from stress alone. No gears were stripped, and in fact no visible damage was seen anywhere in the mechanism. The team is currently unable to explain the failure, other than to say that the stresses may have been so great that the plastic deformed enough that the gears were no longer meshed tightly.

This isn’t the first time we’ve checked in with the team at [Gear Down For What?], just a few months ago they impressed us by lifting an anvil with one of their printed mechanisms. They’re also not the only ones curious to find out just how far 3D printed plastic can go.

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The Fine Art Of Heating And Cooling Your Beans

October 16, 2017 by Tom Nardi 27 Comments

They say that if something is worth doing, it’s worth doing right. Those are good words to live by, but here at Hackaday we occasionally like to adhere to a slight variation of that saying: “If it’s worth doing, it’s worth overdoing”. So when we saw the incredible amount of work and careful research [Rob Linnaeus] was doing just to roast coffee beans, we knew he was onto something.

The heart of his coffee roaster is a vortex chamber with an opening on the side for a standard heat gun, and an aperture in the top where an eight cup flour sifter is to be placed. [Rob] modeled the chamber in Fusion 360 and verified its characteristics using RealFlow’s fluid simulation. He then created a negative of the chamber and printed it out on his Monoprice Maker Select 3D printer.

He filled the mold with a 1:1 mix of refractory cement and perlite, and used the back of a reciprocating saw to vibrate the mold as it set so any air bubbles would rise up to the surface. After curing for a day, [Rob] then removed the mold by heating it and peeling it away. Over the next several hours, the cast piece was fired in the oven at increasingly higher temperatures, from 200 °F all the way up to 500 °F. This part is critical, as trapped water could otherwise turn to steam and cause an explosion if the part was immediately subjected to high temperatures. If this sounds a lot like the process for making a small forge, that’s because it basically is. Continue reading “The Fine Art Of Heating And Cooling Your Beans” →